The present invention is directed toward an antenna raising and lowering device and more particularly toward a device which is intended to be mounted on top of an emergency vehicle for remotely raising and lowering the two-way communication antenna thereof.
As a result of the additional equipment being added to emergency vehicles such as ambulances, fire engines, rescue squads and the like, the more modern vehicles are being made larger than older vehicles. This has created a serious problem with respect to two-way communication antennas which extend upwardly from the top of the vehicle. The problem results from the fact that while the vehicles are becoming larger, they continue to be garaged in existing firehouses and garages with existing door openings which, in many cases, have a height designed for the older and smaller vehicles. With only a small clearance between the top of the vehicle and the garage openings, antennas are frequently broken. This not only adds a significant expense but can seriously interrupt emergency aid while the two-way communication system is being repaired.
Numerous attempts have been made to provide a remotely controlled mobile antenna raising and lowering device. Most of these prior art devices, however, require substantial modifications to the vehicle in order to connect the device to the same. Other prior devices known to Applicant are intended to be mounted within the vehicle and therefore take up substantial space which could be put to other use.
U.S. Pat. No. 4,101,897 describes a collapsible mobile antenna system which is intended to be mounted on top of a vehicle. The system shown in this patent, however, is not motor driven but must be manually operated from outside the vehicle. Accordingly, this system could not be used while the vehicle is in motion.
The antenna raising and lowering device shown in U.S. Pat. No. 3,224,003 is motor driven. However, there is a direct interconnection between the motor and the antenna. As a result, if the antenna is in the down position and a defect in the motor system occurs, the antenna cannot be raised, thereby rendering the communication system inoperative. Furthermore, movement of the antenna is directly proportional to rotation of the motor which can result in very slow operation of the antenna.
In addition to all of the foregoing defects of the prior art known to applicant, applicant is not aware of any prior antenna raising and lowering devices which include a means for providing a ground plane for the antenna. Such a ground plane is very often necessary when the structure on which the antenna raising and lowering device is mounted does not provide an adequate natural ground plane.